System for unbalanced magnetron sputtering with AC power

Abstract

An array of unbalanced magnetrons arranged around a centrally-located space for sputter coating of material from target electrodes in the magnetrons onto a substrate disposed in the space. The electrodes are powered in pairs by an alternating voltage and current source. The unbalanced magnetrons, which may be planar, cylindrical, or conical, are arranged in mirror configuration such that like poles are opposed across the substrate space or are adjacent on the same side of the substrate space. The magnetrons are all identical in magnetic polarity, such that there is no magnetic coupling between either opposed or adjacent magnetrons. A positive plasma potential produced by the AC driver prevents electrons from escaping to ground along the unclosed field lines, increasing plasma density in the background working gas and thereby improving the quality of coating being deposited on the substrate.

What is claimed is:  
     
         1 . A system for sputter coating a film of material onto a substrate, comprising: 
 a) an array including first and second unbalanced magnetrons having the same north and south magnetic polarities and being arranged in mirror configuration defining a space for receiving said substrate therebetween such that like poles are opposed without magnetic coupling between said magnetrons in said array, each of said magnetrons including an electrode target formed of said material; and    b) an alternating current and voltage power source electrically connected to said first and second electrode targets for alternatingly energizing said targets as cathodes and anodes.    
     
     
         2 . A system in accordance with  claim 1  wherein each of said magnetrons has both north and south pole pieces, and wherein said north pole pieces have a larger magnetic cross-section than said south pole pieces.  
     
     
         3 . A system in accordance with  claim 1  wherein each of said magnetrons has both north and south polepieces, and wherein said south pole pieces have a larger magnetic cross-section than said north pole pieces.  
     
     
         4 . A system in accordance with  claim 1  wherein the frequency of said alternation is a radio frequency.  
     
     
         5 . A system in accordance with  claim 1  further comprising a reactive gas for reacting with said target material during sputtering thereof to form a compound of said target material and said gas on said substrate.  
     
     
         6 . A system in accordance with  claim 1  wherein said first and second unbalanced magnetrons are planar magnetrons.  
     
     
         7 . A system in accordance with  claim 1  wherein said first and second unbalanced magnetrons are cylindrical magnetrons.